components of the Milky Way



radius
% light
% mass
age
metal
abundance
rotation
speed
halo
100 kpc
0
95
11 - 13 Gyr
poor
-4 < dex < -3
negligible
thick disk
2 kpc
2
0.2
10 - 11/12 Gyr
intermediate
-2.2 < dex < -0.5
170 km/s
thin disk
0.6 kpc
90
5
1 - 10/11 Gyr
rich
-0.5 < dex <  0.3
220 km/s
extreme disk
(star formation)
0.2 kpc
7
< 1
< 1 Gyr
very rich
 dex < 1.0
220 km/s
bulge
(bar-shaped?)

1
<1
8 - 13.6 Gyr


black hole

0
0
13.6 Gyr ??